The first victim of Toulouse Islamist Mohamed Merah refused to follow his demands to lie down on the ground and was shot at point-blank range.
Merah murdered seven people last March and filmed each killing. Now a transcript has emerged of the moments before he shot dead Imad Ibn Ziaten.
Before he was shot, the soldier told Merah to put his gun away, reports say.
Merah went on to murder two other soldiers and then an adult and three children at a Jewish school.
The three deadly attacks, which took place in rapid succession between 11 and 19 March 2012, shocked France. He was killed in a police siege at his flat in Toulouse.
According to excerpts of a transcript of a video filmed by Merah on a portable camera worn on his chest, he challenged the parachutist before pulling out his gun, asking him: "Are you in the army? Are you a soldier?".
The dialogue between the two men and the subsequent shooting were recorded by Merah on the camera he had attached to his chest.
"Lie face down. I'm not messing around, lie face down," Merah tells him a few minutes later.
But Imad Ibn Ziaten refused, facing his killer and telling him. "I'm not going to lie face down... I'm staying here. You're going to shoot? Go on then, shoot."
According to the transcript, a gun is heard to go off.
Merah repeats "Allah is great!" several times. The gun is fired again and Merah then heads off on his scooter before returning. He says to his victim: "That is Islam, my brother: you kill my brothers, I kill you".
Imad Ibn Ziaten's mother, Latifa, told French newspaper Le Figaro that she wanted people to know how her son had died.
"This is not Islam," she said. "And my son, though he was a soldier, had never killed anyone."
French intelligence had been monitoring Merah as a suspected Islamist militant following trips he made to Pakistan and Afghanistan.
Cornered by police, he reportedly told negotiators he was a member of al-Qaeda.
According to French prosecutors, he expressed no regrets other than "not having claimed more victims" and was proud of having "brought France to its knees".
He said he had been motivated by the fate of the Palestinians, the French military presence in Afghanistan and France's ban on the full veil.